I am going to put a ban on what sized graphics you can have as your avatar and signature.
Avatar: 150x200px
Single Signature: 500x300px
Couple Signature: 600x300px
Family Signature: 800x300px
Those are all the limits for what sized graphics you can have as your avatar or signature. Please make sure you keep to them or I will be forced to re-size them myself. If you want to put larger graphics in your signature then put them under a spoiler.
Otherwise, you can use the 'Artist's Corner' to post your own graphics.